Cutting apparatus for a circular knitting machine

ABSTRACT

YARN FED TO, AND KNITTED BY, THE NEEDLES OF A NEEDLE CYLINDER, IS TRANSPORTED BY A ROTATING CUTTER RING TO A STATIONARY CUTTING MEANS. THE PORTION OF THE CUTTER RING BEFORE THE CUTTING MEANS IS COVERED SO THAT THE YARN IS NOT IMMEDIATELY CUT, BUT PASSES FIRST THE CUTTING MEANS BY, AND IS TRANSPORTED UNTIL IT AGAIN ARRIVES AT THE CUTTING   MEANS WHEREBY YARN ENDS OF SUFFICIENT LENGTH REMAIN AND ARE HELD BY HOLDING MEANS WITHIN THE CUTTING RING.

Jan. 26, 1971 FETZER 3,557,5'

CUTTING APPARATUS FOR A CIRCULAR KNITTING MACHINE Filed March 14, 1969.4 Sheets-Sheet 1 INVIENTOR mum z Fem BY mm ff/L-A a ATTORNEY R. FETZERCUTTING APPARATUS FOR A CIRCULAR KNITTING MACHINE Filed llarbb 14., 1969Jan. 2 1971* 4 Sheets-Sheet 2 y F/GIZ INVENTOR Elam/ 19 PM aw.

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R. FETZER CUTTING APPARATUS FOR A CIRCULAR KNITTING'MACHiNE Jan. 26,1971 Filed Hal-9h 14, 1969 INVENTOR 2mm z-rww ATTORN EY R. Fmzm 355mm VCUTTING APPARATUS FOR A CIRCULAR KNITTING MACHINE I 4 Shets-Sheet AFiled March- 14 1969 mvzmon fi e/mp Fens/a BY Warm/1km,

ATTORNEY United States Patent 1 3,557,578 CUTTING APPARATUS FOR ACIRCULAR KNITTING MACHINE Richard Fetzer, Denkendorf, Germany, assignorto Gottlieb Eppinger, Denkendorf, Germany Filed Mar. 14, 1969, Ser. No.807,457 Claims priority, application Germany, Mar. 14, 1968,

Int. Cl: D04b 15/60 US. Cl. 66-140 Claims ABSTRACT OF THE DISCLOSUREYarn fed to, and knitted by, the needles of a. needle cylinder, istransported by a rotating cutter ring to a stationary cutting means. Theportion of the cutter ring before the cutting means is covered so thatthe yarn is not immediately cut, but passes first the cutting means by,and is transported until it again arrives at the cutting means wherebyyarn ends of sufiicient length remain and are held by holding meanswithin the cutter ring.

BACKGROUND OF THE INVENTION The present invention relates to a circularknitting machine provided with a series of yarn feeding stations spacedabout the needle cylinder of a rotary knitting machine, and selectivelyfeeding or withholding yarns from the knitting needles.

It is known to provide circular knitting machines having a singlefeeding device with a cutting apparatus for automatic cutting of 2. fedyarn when no longer needed. The US. Pat. 2,824,436 discloses a cuttingapparatus for a circular knitting machine in which a stationary knifewithin the circular row of cylinder needles is disposedcircumferentially spaced from the yarn feeding device, and cooperateswith a cutter ring rotating within the circular row of needles at thesame speed as the needle cylinder. When yarn is no longer needed, andthe yarn feeding device retracted, the yarn portion extending betweenthe retracted feeding device and the last operative needle passesthrough a notch between peripheral teeth of the cutter ring, istransported by the same until reaching a clamping device and the knife,and is cut. When the yarn is again needed, the feeding device moves to afeeding position in which the clamped yarn end can be caught by theneedles, and also by the teeth of the rotating cutter ring. When thefirst yarn carrying needle arrives at the knife, the same is operatedfrom the pattern drurn to cut off the yarn in cooperation with the teethof the cutter ring.

It is necessary to dispose the stationary knife and the clamping devicebetween two feeding stations, so far behind the feeding station whichleads in the direction of rotation, that when the yarn is no longer tobe fed to the needles, the portion of the yarn between the eye of. thefeeding device and the last operative needle has, after the cut, alength sufficient for being clamped by the clamping means so that theyarn remains in a position of readiness for its next use and operationby the feeding device. If a plurality of feeding stations is arrangedabout the circumference of the needle cylinder, the distance between thestationary knife and the clamping device of the preceding feedingstation becomes so ICC small, that the cut-off yarn end cannot begripped by the clamping device.

From this follows that it is desirable to obtain such a length of thecut-off yarn end that the cut-off yarn end can be reliably clamped orheld, which means that the length of the cut-off yarn end must begreater than the distance between the stationary knife and the precedingfeeding device.

SUMMARY OF THE INVENTION It is one object of the invention to provide acutting apparatus for automatically cutting fed yarns in such a mannerthat yarn ends of sufficient length remain.

Another object of the invention is to provide a cutting apparatusparticularly suitable for a circular knitting machine having a pluralityof feeding devices.

Another object of the invention is to prevent cutting of the yarnimmediately upon feeding or withdrawing the same.

Another object of the invention is to provide means for cutting yarn fedto the needles of a circular knitting machine in such a manner that thecutoff yarn end has at least a desired minimum length.

With these objects in view, the present invention provides a stationarycover, preferably carrying a'. cutter, extending between the same, and afirst yarn guide of the preceding feeding device, and covering acorresponding portion of a rotary cutter ring which cooperates with thestationary cutter.

One embodiment of the invention comprises a series of stationary feedingdevices spaced about a needle cylinder, each feeding device having atleast one yarn guide; a stationary cutting means located between twosuccessive feeding devices; a cutter ring rotating with the needlecylinder having a peripheral rim with teeth cooperating with the cuttermeans; holding means, preferably including a suction means, locatedwithin the cutter ring for holding yarn ends; and cover means forcovering a portion of the peripheral rim located between one of the twofeeding devices and said cutting means.

Upon movement of a yarn guide to a feeding position, the needles catchthe respective yarn and transport the same sliding on the cover means sothat the yarn first passes the cutting means by and is engaged by theteeth behind the same, and then cut after further rotation of the cutterring between the same and the cutting means.

Upon movement of a yarn guide to a retracted position, the guided yarnsliding on the cover means first passes the cutting means so that it istransported by the needles and needle cylinder, then engaged by theteeth behind the cover means, and cut after further rotation of thecutter ring between the same and the cutting means in a position inwhich the cut-off yarn end is held by the holding means, extending tothe respective yarn guide.

Consequently, when a yarn is retracted by the yarn guide, the yarncannot be caught by the rotating cutter ring since in this regionpreceding the stationary cutting means, the teeth of the cutter ring arecovered. When a yarn guide is moved to the feeding position, the yarn isplaced on the upper edge of the cover means and slides along the sameuntil passing the cutting means, whereupon the yarn is furthertransported by the rotating cutter ring, and finally cut and sucked intothe holding suction device.

In both cases, the cutting of the yarn takes place after substantially"one revolution of the 'needle cylinder. It is advantageous to provide anarcuate upper edge of the cover means which is substantially parallel toa line connecting the upper ends of the needles moving between theknitting position and the cast-off position.

A suction device is provided within the cutter ring above the same andincludes a substantially frusto-conical member whose largest diameter issubstantially equal to the diameter of the base circle of the peripheralteeth of the cutter ring. In the direction of rotation of the needlecylinder, aprojectionis provided at the lower edge of the suction memberfollowing each feeding device, which assures reliable guidance of theretracted, non-operative yarn, into the interior of the frusto-conicalsuction mem her in which negative pressure prevails.

The cover means has the form of a curved arm carrying at one end thecutting means in the form of a pivotally mounted'cutter or knife. Aportion of the arm is located outwardly of the peripheral teeth of thecutter ring,

and following the curvature of the same. The other end of, the arm isconnected with a slide which is guided for vertical movement biassed bya spring toward the peripheral rim of the cutter ring. Since the knifeor cutter is mounted for pivotal movement about an axis tangential tothe base circle of the peripheral teeth of the cutter ring, and parallelto the top surface of the same, full abutment of the cutting edge of thecutter on the top surface of the cutter ring is assured.

Due to the fact that the stationary cutter follows the respectivefeeding device in the direction of rotation of the needle cylinder,retraction of the yarn by the yarn guide of the respective feedingdevice causes the catching of the yarn between two adjacent teeth of thecutter ring only behind the respective knitting system. Therefore, theyarn length between the retracted yarn guide and the cutter is alsolonger than the distance between the respective knitting system, whichis followed by the cutter, and the knitting system preceding the same.

Thenovel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic plan viewillustrating the cutting apparatus of the invention provided in acircular knitting machine having eight feeding stations and knittingsystems;

FIG. 2 is a fragmentary perspective view illustrating the cuttingapparatus of FIG. 1, and also showing a suction device;

FIG. 3 is a vertical view taken on line III-III in FIG. 4,- andillustrating on an enlarged scale, a device for mounting the covermeans;

FIG. 4 is a front view of the device shown in 'FIG. 3; FIG. 5 is afragmentary plan view of the device of FIG. FIG. 6 is a fragmentaryperspective view illustrating the different positions of the yarn guidesof a feeding device;

FIG. 7 is a schematic side view illustrating cutting of a yarn adjacentthe needles; and

FIG. 8 is a fragmentary perspective view illustrating three differentoperational positions of a newly-fed yarn.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As best seen in FIG. 1, eightfeeding devices I to VIII are arranged in a circle around needlecylinder 21, see FIG. 3, which carries a circular row of needles 13.Each feeding device I to VIII is associated with the needles between thesame and the next following feeding device, and includes a plurality ofyarn guides 11 and 12, feeding devices I and VIII including a third yarnguide 20. The number of yarn guides has no bearing on the invention.

As best seen in FIGS. 3 to 5, a cutter ring 1 has a peripheral rimprovided with uniformly spaced teeth In. The cutter ring 1 is connectedwith needle cylinder 21 for synchronous rotation, and is mounted on adisc 15 provided with radial channels in which sinkers 16 are mountedfor radial movement. Disc 15 and sinkers 16 also turn in synchonism withneedle cylinder 21 and needles 13 about a common axis.

A stationary cutter 2 cooperates with the teeth 1a so that yarn locatedbetween two teeth 1a is cut by cutter 2 when cutter ring 1 has turned toa position in which the yarn engages the stationary cutter 2. The bottomface of cutter 2 abuts the top surface of the toothed rim 1a, and slideson the same when cutter ring 1 rotates with the needle cylinder 21 inthe direction of the arrow P in FIG. 1. Cutter 2 is stationary incircumferential direction and in relation to the cutter ring 1, but ismounted on an angular cover means 3 which has an arcuate cover arm witha concave top face 3a, and a part-cylindrical wall 3b located outside ofthe toothed rim 1a and following the circular contour of the same, asbest seen in FIG. 3. Cutter 2 is mounted for free angular movement abouta pivot screw 9 so as to assume a position in which the entire bottomface of cutter 2 slidingly abuts the peripheral toothed rim of cutterring 1. The vertical arm of cover means 3 is secured to a slide 5 whichis mounted for up and down movement in a guide way in a guide member 4to which a closure member 10 closing the guide way is secured, A pin 6projects from the top face of slide 5 through an opening in a supportingbracket 7 which is secured to guide member 4, and a spring 8 is mountedon pin 6 between bracket 7 and slide 5 to urge the same, and therebycover means 3 downward to a position in which the edge of cutter 2resiliently abuts the peripheral rim of cutter ring 1.

The substantially horizontal arcuate cover arm 3a, 3b extends from thefirst yarn guide 11 of feeding device 1 to a point at which the cylinderneedles 13 of the knitting system supplied by feeding device I, are inthe lowest position 13a and begin to move upward to the higher positionof the needles 13b.

The top face 3a of the cover arm has a concave profile matching animaginary line passing through the points of the cylinder needles 13,while the lateral wall 3b is part-circular in a horizontal plane tocover the toothed rim of cutting ring 1.

A suction device is provided which has a downwardly open frusto-conicalhood 14 in which negative pressure prevails. The lower edge of suctionhood 14 has projections 14b which are adapted to engage yarn passingthrough the yarn guide of the feeding device.

A suction tube 14m, shown in FIG. 1, is located within suction hood 14and produces low pressure in the same. Cut-off yarn ends are sucked intosuction tube 14m which has an extension 142, and serves as a holdingmeans for the cut-off yarn ends. The suction opening of tube 14m, Me islocated eccentric to the axis of the needle cylinder close to the loweredge 14a of suction member 14 which serves as a hood for suction tube14m.

Assuming that a yarn 12a which passes through a yarn guide 12 in thelower feeding position is caught by the needles 13 as shown in FIGS. 2and 8, the yarn portion 12a extending between the eye of yarn guide 12and the suction tube 14m, see FIG. 1, in a position of readiness, ismoved in circumferential direction of the arrow P by the needles 13 ofthe rotating needle cylinder 21 while yarn portion 12a slides on theupper concave face 3a'of cover arm 3 beyond the cutter 2. Due to thefact that the profile of face 3a matches the position of the needlehooks, the yarn portion 12a is not tensioned. When yarn portion 12a haspassed the end of cover arm 3a, 3b, and cutter 2, it moves inward due toits tension and is caught by the peripheral teeth 1a. FIG. 8 shows threepositions of the yarn supplied by yarn guide 12 in the lower feedingposition. In the position 12a, the needle 13 catches the yarn 12a whichextends from yarn guide 12 to the suction holder 14m, as shown in FIG.1, and draws the same to assume an angular position, as shown in FIG. 8since the end of the yarn is further held by the suction tube 14m. Whenthe needle moves toward the position 13 yarn in the position 12b slidesover the top face 3a of the cover arm 3. In the position 13 of the sameneedle, the yarn in the position 12b, 12c is caught by a tooth 1a on theperiphery of cutter ring 1 and further transported by the same sincecutter ring rotates in synchronism with the needle cylinder in thedirection of the arrow P. After substantially one revolution, the yarnend, still held by the pneumatic holding tube 14m is cut off since theyarn arrives again at cutter 2, and since the cut takes place close tothe needle hooks, only a very short cut-off end of the yarn in theposition 11d remains connected with the fabric. When a yarn guide, forexample, yarn guide 11, is moved to the retracted position while theyarn guide 12 is in the feeding position, as shown in FIG. 6, the yarncannot be immediately caught by the teeth of the cutting ring 1, sincethe yarn 11a slides on the outer surface of cover arm portion 3b. Theyarn slides over the end of cover arm 3a, 31), passing cutter 2 by andis caught by the teeth 1a behind the cutter 2 so that the yarn isfurther transported by the cutter ring until again arriving at thecutter 2 so that the same cuts off the yarn in cooperation with theteeth 11a, as shown for the yarn 110. in FIG. 7. After about half arevolution of the needle cylinder, the yarn between the last operativeneedle 13 and the eye of the yarn guide 11, is in the position 110, andafter a complete revolution of cutting ring 1, the yarn is in theposition 110! in which it is cut by cutter 2.

When one of the yarns guided by a yarn guide of feeding device VIII, forexample, the yarn a guided by yarn guide 20, is retracted by the yarnguide 20 to the inoperative position, and is caught between feedingdevice VIII and feeding device I by tooth 1a of cutter ring 1, this yarnis cut by the stationary cutter 2 so that also the yarns of the feedingdevice VIII are cut off a sufficient distance from the feeding deviceVIII, and the yarn end is long enough to be caught by the extension Meof the suction tube 14m, and held by the same.

FIG. 1 illustrates a plurality of yarns 12a in the position of readinessextending between a yarn guide 12 and the suction holding tube 14m, andbeing partly laid about a cylindrical part 140 within the suction hood14.

The length of the cut-off yarn ends mus-t be sufficient for holding thesame by the suction tube 14m, which is of partciular importance when theyarns are highly elastic and are expanded by the knitting needles duringknitting, and consequently contract when out off.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofknitting machines differing from the types described above.

While the invention has been illustrated and described as embodied incutting apparatus for automatically cutting yarns fed to the needles ofa circular knitting machine, it is not intended to be limited to thedetails shown, since various modifications and structural changes may bemade without departing in any way from the spirit of the presentinvention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

I claim:

1. Cutting apparatus for a circular knitting machine, comprising, incombination, a rotary needle cylinder having a circular row of movableneedles rotating therewith; a series of stationary feeding devicesspaced about said needle cylinder, each feeding device having at leastone yarn guide movable between a feeding position for feedin a yarnguided thereby to said needles, and retracted position a stationarycutter located between two successive feeding devices; a cutter ringrotating with said needle cylinder having a peripheral rim adjacent saidneedles and formed with teeth cooperating with said cutter; holdingmeans located within said cutter ring for holding yarn ends passingthrough said yarn guides; and cover means for covering a portion of saidperipheral rim located between one of said two feeding devices and saidcutter so that upon movement of a yarn guide from said one feedingdevice to said feeding position, said needles catch the respective yarnand transport the same sliding on said cover means so that said yarnfirst passes said cutter by and is engaged by said teeth behind thesame, and is then cut after further rotation of said cutter ring betweenthe same and said cutter, and so that upon movement of a yarn guide fromsaid one feeding device to said retracted position, the guided yarnsliding on said cover means first passes said cutter by and is engagedby said teeth behind the same and cut after further rotation of saidcutter ring between the same and said cutter in a position in which thecut-off yarn end is held by said holding means.

2. Cutting apparatus as claimed in claim 1 wherein said cover meansincludes a cover arm covering said portion of said peripheral rim andhaving a concave top surface whose contour matches a line passingthrough the ends of said needles adjacent the respective portion of saidcutter ring, and also has a part-cylindrical side wall located outsideof and parallel to, said peripheral rim of said cutter ring.

3. Cutting apparatus as claimed in claim 1 wherein said cover meansincludes a cover arm covering said portion of said peripheral rim; andwherein said cutter is mounted on one end of said cover arm remote fromsaid one feeding device.

4. Cutting apparatus as claimed in claim 3 including resilient meansbiasing said cover arm toward the top face of said peripheral rim ofsaid cutter ring so that the bottom face of said cutter slidingly abutssaid peripheral rim and cooperates with said teeth to cut yarns.

5. Cutting apparatus as claimed in claim 4 comprising a stationarysupport having a vertical guide way, a slide mounted in said guide wayand carrying the other end of said cover arm, and wherein said resilientmeans is a spring between said slide and said support and urging saidslide with said cover arm and cutter downward into abutting engagementwith the top face of said peripheral rim of said cutting ring.

6. Cutting apparatus as claimed in claim 1 and including a pivot meansmounting said cutter on said cover means for turning movement about anaxis tangential to the base circle of the teeth of said peripheral rim,and parallel to the top surface of said cutter ring.

7. Cutting apparatus as claimed in claim 1 wherein said holding meansincludes a suction tube located within said cutter ring for sucking inand holding cut-off yarn ends.

8. Cutting apparatus as claimed in claim 7 wherein said suction tube hasan inlet means of elongated shape extending between said one feedingdevice and the feeding device preceding the same in the direction ofrotation of said cutter ring.

9. Cutting apparatus as claimed in claim 1 comprising a suction hoodhavin an annular bottom edge adjacent said peripheral rim of said cutterring, said bottom edge having a series of recesses whose number is thesame as the number of feeding devices, and which are adapted to engageyarn extending from said yarns guides and wherein said holding meansinclude a suction tube located within said suction hood for sucking inand holding cut-off yarn ends extending to said yarn guides,respectively.

10. Cutting apparatus as claimed in claim 9 wherein said cover meansincludes a cover arm having a concave top face and a side wall parallelto said portion of said peripheral rim and located outside of the same;wherein said cutter is pivotally mounted at the end of said arm remotefrom said one feeding device; comprising means mounting the other end ofsaid arm for vertical movement with said cutter toward said peripheralrim, and resilient means biasing said arm with said cutter so that saidoutter slidingly engages the top face of said peripheral rim.

References Cited UNITED STATES PATENTS ROBERT R. MACKEY, PrimaryExaminer

